The Basic Construction of a DC Generator for a Wind Turbine
Wind power generation on a micro scale to generate power for buildings is possible in some locations and a key component of this is the DC Generator. Some other applications they are used in are, general lighting, battery charging and small power supplies. These types of DC generators generally give a constant voltage for small operations.
DC generators give out a direct current, which means the current only flows one way, unlike AC which alternates. The main principle is to convert mechanical energy into electrical energy. The way it produces this energy is that it is based on the fundamental principles of Faraday’s Law of electromagnetic induction, in which when a conductor moves in a magnetic field of any strength it cuts magnetic lines of force, due to which an EMF is induced in the conductor. The EMF will cause the current to flow if the conductor circuit is closed. This means the magnitude of this induced EMF depends upon the rate of change of flux linkage. This means the essential parts of the generator are a magnetic field and conductors which move inside the magnetic field.
Inside a DC generator there is a main outside frame called the Yoke which is the casing for the generator as well as providing support for the poles, connected to the Yoke are many Pole Cores that spread out the flux in the air gaps and reducing resistance of the magnetic path. On the Pole Cores are Pole Coils that will have lots of copper wire wrapped round the frame to produce the magnetic flux once a current is passed through the coil.
Moving directly to the centre of the Yoke is the Armature Core which houses the Armature Conductor that looks much like long gear cogs that are die cut and inside these cogs there are air gaps, as well as a keyhole – these are the parts that rotate in the centre to cut lines in the magnetic force. The Armature Windings are then wrapped round the core to make a coating. At the end of the Armature Core is the Commutator this piece of equipment facilitates the collection of current from the Armature Conductors which then coverts the AC current into unidirectional current. Finally, the last component is the Brushes which collect the current that is in the commuter and the bearings.
All these components together including the air gap between the Pole Cores and the Armature Core make up the magnetic circuit. The Armature Cores are mounted over the rotating part or otherwise known are the Shaft.
The use of wind power generation is cost effective and is on the rise in rural areas, in some cases it actually pays for itself when it exports electricity back to the grid.